Radiation risks from X-rays has led to criticism of Tesco’s promotion of vouchers for CT health scans through its Clubcard loyalty scheme.
The Society of Radiographers said the Lifescan promotion, billed as helping to detect tumours and other illnesses, is “inappropriate” and does not make the risks from radiation exposure clear.
Spokesman Richard Evans told the BBC: “I wouldn’t want to underplay the sense of relief if something positive and dangerous is found and dealt with in good time.
“However, for every one of those there’ll be an untold number who are taking up a GP appointment slot for no real reason.”
He said they would also cause people to experience “unnecessary anxiety” if they find apparent abnormalities that then prove to be harmless.
Tesco said the firm it uses to provide the scan service - Lifescan - employed qualified staff and explained any risks to customers.
Lifescan spokesman Dr John Giles said: “There’s no evidence of any harmful effect from that kind of exposure, otherwise I suppose we’d have to have health warnings up on the signs driving into Cornwall.”